JPH04201014A - Electric discharge machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrical discharge machining apparatus that processes a workpiece while appropriately controlling the gap between the workpiece and an electrode.

[Prior Art] FIG. 39 is a connection diagram of a discharge circuit of a conventional electric discharge machining apparatus. In the figure, (1) is an electrode, and (2) is a workpiece placed at a predetermined distance from the electrode (1).

(3) is the first DC power supply that can variably set the output voltage (Ell), (4) is the diode, (5) is the current limiting resistor, and (6) is the first switch circuit 1, for example, a semiconductor switch. The electrode (1) is connected to the anode of the diode (4), and the negative of the diode (4) is connected to the first DC power source (3).
The anode of the first DC power supply (3) is connected to one end of the current limiting resistor (5), and the current limiting resistor (5) is connected to the cathode of the first DC power source (3).
5) the other end is connected to the anode of the semiconductor switch (6),
The cathode of the semiconductor switch (6) is connected to the workpiece (2). (7) is a control circuit 1, for example, a single oscillation circuit. An output terminal (7a) of this oscillation circuit (7) is connected to a control terminal (6a) of a semiconductor switch (6).

FIG. 40 is a detailed connection diagram of the nine oscillation circuit (7). In the figure, (4001) is a clock pulse generator, +
4002+, +4003+ and 14004) are two-man OR circuits, (40071 is a flip-flop circuit,
(40081 is on-time counter, +4009)
is the off-time counter.

F4010), the output terminal (7a) of the oscillation circuit (7) is
On-time setting device to set the time for 1゛°, +4
011+ is an off-time setter that sets the time when the output terminal (7a) of the oscillation circuit (7) becomes 0''.The on-time setter +4010) is an on-time counter (4010).
The off-time setter (40111) has the same number of output terminals as the bit number of the off-time counter (400
It has the same number of output terminals as the number of bits of 9+. (4
0121 and +401] is a match comparison circuit. This coincidence comparison circuit +401.2+ is an on-time counter +4
It has a pair of comparison data input terminals having the same number of input terminals as the number of bits of 0081. Each output terminal of the on-time setter noto+ is connected to the coincidence comparison circuit +40.
12+, and each output terminal of the on-time counter 14008+ is connected to the other comparison data input terminal.

The match comparison circuit +4012+ is an on-time setter (401
The on-time data set to 0) is compared with the contents of the on-time counter +4008+, and when the two match, "1" is output to the output terminal (4012a).

When the content of the on-time counter (40081) reaches a preset value, the output terminal (4012b)
Outputs "l" to

Furthermore, the coincidence comparison circuit +4013+ has a pair of comparison data input terminals having the same number of input terminals as the number of bits of the on-time counter (4009).Then, each output terminal of the off-time setting device (4011) Comparison circuit (
One of the off-time counters 4013+ is connected to a comparison data input terminal, and each output terminal of the off-time counter +4009+ is connected to the other comparison data input terminal.

In addition, the - number comparison circuit (4013) is the off-time setter 1.
The output terminal (
4013a) outputs 1''.

N output terminal (4007) of flip-flop (4007)
Aal is connected to one input terminal of the two-man power AND circuit (4005), and is also connected to the output terminal (7) of the oscillation circuit (7).
a). In addition, a two-person AND circuit (40
The other input terminal of 05) is the clock pulse generator +40
01+ output terminal (connected to 4001al).

Furthermore, the output terminal of the two-man power AND circuit (40051 is the count input terminal f4 of the on-time counter +4008+)
008a).

C output terminal +4007 of flip-flop f4007+
b) is connected to one input terminal of the two-man power AND circuit +4006+, and the other input terminal of the two-man power AND circuit (4006) is connected to the output terminal f4001a) of the clock pulse generator 14001). Also, two-person AND
The output terminal of the circuit +4006) is the off-time counter +4
Count input terminal of 0091 (connected to 4009al).

The output terminal f4012a) of the -number comparison circuit 14012+ is connected to one input terminal of the two-man power output circuit (4003) and also to one input terminal of the two-man power OR circuit +40021. Furthermore, 2-person OR circuit +400
2] is connected to the R input terminal +4007c) of the flip-flop (4007), and the two-man OR circuit [4007c] is connected to the R input terminal of the flip-flop (4007).
003! The output terminal is on-time counter +4008+
is connected to the reset input terminal (4008b) of.

In addition, the output terminal f4013 of the negative number comparison circuit +40131
a) is connected to one input terminal of the two-man OR circuit (4004) and S of the flip-flop +40071.
input terminal +4007d). Furthermore, 2
The output terminal of the human OR circuit (4004) is the reset input terminal (4009bl) of the off-time counter (40I3).
It is connected to the.

The reset terminal (7d) of the oscillation circuit (7) is the other input terminal of the two-person OR circuit +4002+, and the two-person OR circuit +4.
The other input terminal of 003+ and the two-man OR circuit+
4004). Furthermore, the output terminal +4012bl of the negative number comparison circuit +40121
is connected to the output terminal (7b) of the oscillation circuit (7).

Next, the operation of the oscillation circuit (7) shown in FIG. 40 will be explained.

At the beginning, the flip-flop +4007] is reset, and the C output terminal 14 of the flip-flop +4007) is reset.
007b) is II I 11, and the N output terminal (40
Assume that 07al is 0''. Since a clock pulse of a predetermined period is always output to the output terminal (4001al) of the clock pulse generator +4001,
The clock pulse is inputted to the count input terminal (4009al) of the on-time counter + 4009 through the two-manual AND circuit (4006).The off-time counter (4009) counts up each time a clock pulse is manually applied. When the contents of the off-time counter +4009+ become equal to the contents of the off-time setter +4011+, that is, the off-time data, the coincidence comparison circuit (40
The output terminal 14013a) of 13) becomes “■” and the off-time counter +4 is output via the two-man OR circuit (4004).
009+ reset input terminal +4009bl '1'
and reset the off-time counter +4009]. At the same time, the flip-flop +4007) is set.

When the flip-flop (40071 is set, the C output terminal of the flip-flop + 40071 + 4007b) becomes "O", and the N output terminal f4007a) becomes "O".
1”. Therefore, 2-person AND circuit +4006
No clock pulse is output to the + output terminal, and the off-time counter +4009) stops counting. On the other hand, a clock pulse is output to the output terminal of the two-man power AND circuit (4005), and the on-time counter (4008+
starts counting.

When the contents of the on-time counter +4008+ reach a predetermined value set in advance, the match comparison circuit +4012
A pulse is output to the + output terminal t4012b). This pulse is output to the output terminal (7b) of the oscillation circuit (7). Also, the on-time counter +4008+ continues counting, and when it becomes equal to the on-time data set in the on-time setter +40101, the coincidence comparison circuit +
The output terminal f4012a) of 4012+ becomes ``'1 pin. When the output terminal t4012a) becomes 1p, two-man OR
On-time counter +400 via circuit +4003)
81 reset input terminal (set 4008bl to “1”,
At the same time, the R input terminal f4007c) of the flip-flop +4007) is set to 1" via the two-man OR circuit f4002+, and the flip-flop +40071 is reset. Therefore, here, the on-time counter (4008) is reset. ), off-time counter +4009), and flip-flop +40071 are all reset, returning to their initial state.

After that, the above operation is repeated, resulting in 7 oscillation circuit (7)
The output terminal (7a) is equipped with an on-time setting device f4010.
A pulse is output that becomes "I" during the on-time data set to 1, and becomes "0" during the off-time data set in the off-time setter (4011).

A pulse or pressure is applied to the output terminal (7b) after a predetermined time after the output terminal (7a) changes to "1".

Note that if a reset pulse is applied to the positive terminal (7d) of the oscillation circuit (7) while the flip-flop (4007) is set, the flip-flop +40071 is reset. Also, flip-flop (4007)
The C output terminal (+4007b) of is connected to the output terminal (7C) of the oscillation circuit (7).

In FIG. 39, (8) is a diode, and (9) is a third DC power supply having an output voltage (E3). Also,
not is the third switch circuit 2, for example, a semiconductor switch. The anode of the diode (8) is connected to the electrode (1), and the cathode of the diode (8) is connected to the third DC power source (9
), the anode of the third DC power source (9) is connected to the anode of the semiconductor switch (10), and the cathode of the semiconductor switch (10) is connected to the workpiece (2). (11), (12+ is a voltage dividing resistor, and 9 voltage dividing resistor is 1) One end is connected to the electrode (1), the other end is connected to the - end of the voltage dividing resistor (12), Furthermore, the other end of the 5-part voltage resistor (12) is connected to the workpiece (2). (13) has two input terminals (13a
l and 113b),
(14) is a discharge detection circuit. Differential amplifier (13
) is connected to the connection force t12af between the voltage dividing resistor (11) and the voltage dividing resistor 112), and the input terminal f13b) of the differential amplifier (13) is connected to the connection force of the voltage dividing resistor (11) and the voltage dividing resistor 112), b is connected. Also, a differential amplifier (
13) pressure terminal t13c) is the discharge detection circuit (14)
is connected to the input terminal 114al of.

(15) is one-shot multi-buy break, +1
6+ is a two-person AND circuit. 2 person AND circuit is 6
) is connected to the output terminal (7b) of the oscillation circuit (7), and the other input terminal 116b) is connected to the output terminal 4bl of the discharge detection circuit (14). Also, the pressure terminal (16) of the 2-input circuit (16)
c) is connected to the input terminal t15a) of the one-shot multi-bye break (15), and the output terminal of the one-shot multi-bye break (15) is 5. b) is connected to the control terminal float of the semiconductor switch (10). In addition.

(17) indicated by the dotted line is the electrode (1) and the workpiece (2
) shows the stray capacitance between

Next, the operation of the circuit shown in Section 39 will be explained with reference to the operation time chart of FIG. 41.

The oscillation circuit (7) oscillates with a predetermined period fTa and outputs the voltage waveform shown in FIG. 41 (tb) to the output terminal (7a). This voltage waveform has a period of Tb “1”,
This is a pulse waveform that is “o” during the period Tc. This pulse waveform is applied to the control terminal (6a) of the semiconductor switch (6), turning the semiconductor switch (6) on for a period of Tb and turning off for a period of Tc. When the semiconductor switch (6) is on, the voltage fE11 of the first DC power supply (3) is applied to the electrode (1) and the target substance (2) via the current limiting resistor (5) and the diode (4). (hereinafter referred to as the machining gap) to start electric discharge.

FIG. 41 (The waveform of al shows the machining gap voltage (hereinafter referred to as machining gap voltage (Egl). This waveform shows the machining gap voltage after the semiconductor switch (6) is turned on until the electric discharge starts. The gap voltage (Eg) becomes the voltage of the first DC power supply (3), and with the start of discharge, the machining gap voltage fEg) decreases and changes to a predetermined voltage tVgl.

The machining gap voltage (Eg) is applied to both ends of the voltage dividing resistor (12).
Since a voltage proportional to The discharge detection circuit (14)
Based on this voltage, the machining gap voltage (Egl) is set to the first voltage (ESII) and the second voltage (E
It is determined whether the voltage is between S2). The machining gap voltage (Eg) is the first voltage fEsl) and the second voltage (E
S2), it is assumed that a discharge is occurring and the discharge detection circuit (14) outputs 1 to the output terminal f14b).
” is output. Also, the machining gap voltage (Eg) is output.

If the voltage is not between the first voltage fEs1) and the second voltage (ES2), it is assumed that no discharge is occurring, and the discharge detection circuit (14) outputs "0'' to the output terminal (14b).
Output.

Figure 41 (dl shows the voltage waveform of this output terminal +14b), Figure 41ff) shows the output terminal (of the oscillation circuit (7))
7b) shows the voltage waveform outputted in FIG. The voltage waveform of the output terminal (7b) is a pulse waveform that rises with a delay of a predetermined time (Td) from the rise of the output terminal (7a) of the oscillation circuit (7) and falls after a predetermined time (Tej).

Figure 41ff) shows the signal at the output terminal (7b) of the oscillation circuit (7) shown in Figure 41ffl, and the output terminal t14b) of the discharge detection circuit (14) shown in Figure 41ff).
This shows the voltage waveform applied to the output terminal f16cl of the two-man-powered AND circuit (16) as a result of input to each input terminal of the two-man-powered AND circuit (16).

The voltage waveform shown in FIG. 41(e) is input to the input terminal 5a) of the one-shot multivibrator (15). Also, one shot multi-bye break (1
The output terminal f15b) of 5) becomes 1" at the rise of the voltage waveform shown in FIG.
The voltage waveform shown in FIG. 41 fl which returns to 0'' after l is applied. The voltage waveform shown in FIG.
When the voltage waveform in Figure 1 ff) is “■”, the semiconductor switch
(10) is turned on. When the semiconductor switch (10) is turned on, the semiconductor switch (10,) turns on.

A third DC power source (9) is directly connected to the machining gap which is already being discharged via the diode (8), and a discharge current is caused to flow through the machining gap by this third DC power source (9).

FIG. 41 fgl shows a current waveform flowing through the machining gap. This current waveform shows that when either the semiconductor switch (6) or the semiconductor switch (10) is on, the current increases at a predetermined slope, and when both the semiconductor switch (6) and the semiconductor switch (10) are off, It is a falling toothed wave. The reason why the current does not change steeply but at a predetermined slope as shown in FIG. 41(g) is that floating inductance (not shown) exists in the seven circuits. In addition, the output voltage (E3) of the 9 normal third DC power supply (9)
) is set at a higher voltage than the first DC power source (El) to make this slope steeper and allow a larger current to flow.

Now, for example, in such a discharge circuit.

If the discharge is interrupted for some reason while the semiconductor switch (lO) is on, a third DC power supply (
9) output voltage (E3) will be applied.

The machining gap voltage (Egl) increases.Also, even after the semiconductor switch (6) and the semiconductor switch 110 are turned off, the machining gap voltage fEg increases due to the stray capacitance (17), which usually has a size of several thousand to 10,000 PF. ) is maintained at a high voltage.

FIG. 42 shows an operation time chart when discharge is interrupted while the semiconductor switch (10) is on. In the figure, Figure 42 fal to Figure 42 fgl
41 ff) to 41 in FIG. 41, respectively.
(gl) shows the voltage or current waveform at the same measurement point. In Fig. 42, To is the point at which the semiconductor switch (10) is turned on.
, l is the time point when the discharge is interrupted when the semiconductor switch (10) is on, and (T2) is the time point when the semiconductor switch (10) is turned off after the time point (T1). Furthermore, fT3) is again activated by the oscillator (7) after the time point (T2).
) output terminal (7a) becomes 1゛, and the semiconductor switch (
6) is turned on. Also, fT, ) is the time point (
This is the point in time when the semiconductor switch (10) that was turned on at T3) is turned off. In addition, in FIG. 42, the waveforms of FIG. 42(a) to FIG. 41 fl before one time point (T1) are the same as the waveforms shown in FIG. 41.

When an interruption of the discharge occurs at time (T,), Fig. 42fg
The current waveform shown in l decreases to zero and reaches the 42nd
The waveform of the machining gap voltage fEg) shown in Figure ff) is the third
The voltage rises to the pressure voltage (E3) of the DC power supply (9). In addition, the waveform shown in Fig. 42 ff) is the same as the waveform shown in Fig. 42 ff+ at the time point (T2) when a predetermined time (Ton) has elapsed after the rise.
automatically returns to zero. Note that from time point 1 (T2) to time point 1 (T3), the waveform of FIG.
), a high voltage is maintained with almost no drop.

At time (T3), when the output terminal (7a) of the oscillation circuit (7) becomes 1p, the semiconductor switch (6) is turned on.

Starts the next discharge operation. Note that the waveform showing the operation after the first time point (T3) is a waveform in which a normal discharging operation is performed, similar to the waveform shown in FIG. 41.

As shown in Figure 42 (al), the semiconductor switch
If a high voltage is applied to the machining gap due to interruption of discharge while (10) is on, the average machining gap voltage, which is the average voltage of the machining gap, increases.

On the other hand, control to keep the machining gap constant when performing electric discharge machining is achieved by keeping the positive average voltage (hereinafter referred to as average machining voltage) applied to the machining gap constant. is taken. In other words, when the average machining voltage is higher than a predetermined value, the machining gap is narrowed and the average machining voltage is lowered, and when it is lower than the predetermined value, the machining gap is widened (2). The position of the supporting table or the electrode support that supports the electrode (1).

The location has been moved and processing is progressing.

In the discharge circuit shown in FIG. 39, only positive polarity voltage is applied to the machining gap, so the above average machining gap voltage and the above average machining voltage are the same.

Now, if a high voltage is generated in the machining gap because the discharge is interrupted while the semiconductor switch (10) is on, the average machining voltage will rise above the voltage corresponding to the machining gap, so the machining gap can be kept constant. The control that is maintained starts to operate abnormally. In other words, the machining gap becomes abnormally narrow, causing a concentrated discharge, which damages the electrode f1+ and the workpiece (
2) will cause damage and reduce machining accuracy.

7. As a control method to keep the machining gap constant, the no-load time from the time the semiconductor switch (6) is turned on without using the average machining voltage until the discharge starts is measured using a counter, etc. A method of controlling by lengthening and shortening the load time may be considered, but such a method has a large stray capacitance (17), and in electrical discharge machining equipment where the machining fluid is conductive, a current limiting resistor (5) is present. Therefore, after turning on the semiconductor switch (6), it takes time for the machining gap voltage fEgl to rise, and the machining gap voltage (Eg)
It cannot be used because of the problem that the voltage (El) is lower than the voltage (El).

Further, the discharge circuit of the conventional electric discharge machining apparatus shown in FIG. 39 has a first DC power supply (3) and a third DC power supply (9).
However, there are also conventional discharge devices that have only the first DC power source (3). FIG. 43 is a connection diagram of the discharge circuit of such an electric discharge machining apparatus.

In Figure 43, f4301) is the output voltage tE3
51. +4302+ is the first switch circuit 7, for example, a semiconductor switch;
+4303+ is a current limiting resistor. Electrode (1) is the first direct type! +4301+ cathode connected to the first
The anode of the DC power supply f4301+ is a current limiting resistor (43
Connected to one end of 03+, and a current limiting resistor (43031
The other end is connected to the anode of the semiconductor switch +4302+, and the cathode of the semiconductor switch (4302) is connected to the workpiece (
2) is connected to. The output terminal (7a) of the 1 oscillation circuit (7) is the control terminal 1 of the semiconductor switch +4302+.
4302a).

Next, the operation of the discharge circuit shown in FIG. 43 will be explained with reference to the operation time chart shown in FIG. 44.

The output terminal (7a) of the oscillation circuit (7) is connected to the
As shown in l, the period when the output becomes “■” (T44
A pulse waveform in which the period b) and the period [T44C) in which the pressure becomes 0'' is alternately repeated is output. This pulse wave string is connected to the control terminal (4302a) of the semiconductor switch 14302).
), the semiconductor switch (4302+) is input to the period (T
It is turned on at 44bl and turned off at 9 periods (T44c).

FIG. 44 fa) shows the waveform of the machining gap voltage IEg). FIG. 44(a) shows that the voltage rises to E35101 at the rising edge of the bl waveform (T4400).

Voltage (Vgl) at the time point when discharge starts [T4401]
At the time of falling of the waveform in FIG. 44(b) (Ti
The waveform becomes zero at 2O3).

FIG. 44 (cl) shows the waveform of the discharge current.

This waveform is such that the current increases at a predetermined slope from time point +T4401) and decreases to zero at a steep slope from time point 2 (T4402+).

The operation time chart shown in Fig. 44 shows a normal operating state, but Fig. 45 shows one point in time (T44011
At time fT4501) between and time fT4402), the discharging is interrupted due to some reason, and at time 1 (Ti2O3
) is an operation time chart showing an operation when discharging is not restarted even after reaching ).

In Fig. 45, the 1st point fT4402+ at 2 o'clock and the point in time (T
4403), the machining gap voltage fEgl is maintained at the voltage fE3510). The reason why such a high voltage is maintained is the stray capacitance f4 in the machining gap.
This is because electric charge is stored in the terminal 305). Time fT
44021 to time fT44031, the machining gap voltage (
Since Egl is at a high voltage, the average machining voltage is different from the case where no-load time occurs once every predetermined period as shown in Fig. 44, and the machining gap control is not normal. Don't do it.

Further, FIG. 46 is a diagram showing a case in which, in FIG. 45, discharge is interrupted at time (T4501) and then discharge is restarted at time fT4601), which is one time point (Ti2O3) or earlier. In this case, time 1 (T4501) to time (Ti
2O3) is the no-load time, so the no-load time with a high machining gap voltage fEg) occurs twice during one cycle. Therefore, the average machining voltage becomes abnormally high, and the machining gap is not controlled normally.

[Problems to be Solved by the Invention] In the conventional electrical discharge machining apparatus configured as described above, if electrical discharge is interrupted for some reason during electrical discharge, a high machining voltage is generated in the machining gap, and the average machining voltage is reduced. rises abnormally. At this time, the machining gap, which is controlled based on the average machining voltage, becomes abnormally narrow, causing concentrated discharge, which damages the electrode (1) and the workpiece (2), and reduces machining accuracy. occurs.

This invention was made to solve the above-mentioned problems, and the machining gap can be stably controlled.

It is an object of the present invention to provide an electric discharge machining device that can hold an electrode normally and can perform constrained machining with high precision.

[Means for Solving the Problems] An electric discharge machining apparatus according to the present invention includes an electrode disposed facing the workpiece at a predetermined distance, a first DC power supply connected between the electrode and the workpiece, and A series circuit with the first switch circuit, a control circuit that controls the first switch circuit on and off to generate intermittent discharge between the electrode and the workpiece, and a control circuit that controls the first switch circuit on and off to generate intermittent discharge between the electrode and the workpiece, and when the first switch circuit is off The apparatus includes voltage holding means for holding the voltage between the electrode and the workpiece at a predetermined voltage.

Further, the voltage holding means includes a bypass circuit that bypasses the electric charge stored between the electrode and the workpiece.

Further, the voltage holding means includes a second DC power supply and a second switch circuit connected in antiparallel to a series circuit of the first DC power supply and the first switch circuit between the electrode and the workpiece. The circuit consists of a reverse voltage applying circuit which is a series circuit of the following.

Further, the voltage holding means is provided with voltage setting means for setting the output voltage of the second DC power supply so that the average voltage between the electrode and the workpiece becomes a predetermined value.

The voltage holding means includes a changeover switch circuit that switches one terminal of the first DC power supply from the electrode to the workpiece and the other terminal from the workpiece to the electrode, and a resistor connected in series to the changeover switch circuit. It was made to consist of a vessel and a container.

Further, a voltage application time setting means is provided for setting the application time of the voltage by the voltage holding means applied between the electrode and the workpiece so that the average voltage between the electrode and the workpiece becomes a predetermined value. This is how it was done.

Further, a discharge suspension time setting means is provided for setting a discharge suspension time during which application of the discharge voltage is suspended so that the average voltage between the electrode and the workpiece becomes a predetermined value.

Further, a discharge voltage application time setting means is provided for setting the discharge voltage application time so that the average voltage between the electrode and the workpiece becomes a predetermined value.

The present invention also includes a discharge interruption detection circuit that detects that the discharge is interrupted during application of the discharge voltage, and a control circuit that turns off the first switch circuit in response to a discharge interruption detection signal from the discharge interruption detection circuit. This is what I did.

Further, a series circuit of a third DC power supply and a third switch circuit connected in parallel with the series circuit of the first DC power supply and the first switch circuit between the electrode and the workpiece; a discharge detection circuit that detects discharge between the electrode and the workpiece due to the DC power supply;

A circuit is provided that turns on the third switch circuit for a predetermined period of time in response to a discharge detection signal from the discharge detection circuit.

[Operation 1] The electrical discharge machining apparatus configured as described above maintains the machining gap at a predetermined voltage when no electrical discharge is performed in the machining gap.

[Embodiments of the Invention] Embodiment 1 An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a connection diagram showing an embodiment of the present invention.

In Figure 1, (101) is a semiconductor switch (6)
When the semiconductor switch (1O) and the semiconductor switch (lO) are turned off and a voltage is applied to the machining gap based on the first DC power source (3) and the third DC power source (9), the machining gap voltage tE
g) Voltage holding means 9 for setting OV to OV, for example, a bypass circuit. FIG. 1 shows a bypass circuit (101) provided in the discharge circuit of the conventional electrical discharge machining apparatus shown in FIG. 39.

Next, the bypass circuit +101) will be explained with reference to FIG. In the figure, f102+ is a resistor.

(103) is the second switch circuit 1, for example, a semiconductor switch. Also, the resistor is 02) and the semiconductor switch f
The series body of 1031 is connected between the electrode (11 and the workpiece (2). f104) is a two-man power AND circuit, and the output terminal (10
4a) is the control terminal (103a) of the semiconductor switch 03).
connected to l. In addition, a two-man power AND circuit (104
) is connected to the output terminal (7c) of the oscillation circuit (7), and the other input terminal (104c) is connected to the output terminal (7c) of the oscillation circuit (7).
l is connected to the output terminal (15ci) of the one-shot multi-by-break (15).

Note that the bypass circuit (101) includes resistors [102+,
Semiconductor switch + 103) and 2-person AND circuit (1
0,4]. Furthermore, the inverted signal of the output terminal (7a) is output to the output terminal (7c) of the 5 oscillation circuit, and the inverted signal of the output terminal f15bl is output to the output terminal f15c) of the one-way yacht multi-by-break (15). There is.

Next, the operation of the bypass circuit f1011 will be explained with reference to the operation time chart of FIG. FIG. 2 shows T07. when the semiconductor switch (6) and the semiconductor switch (10) are cut off. The operating time chart of the electric discharge circuit of the conventional electric discharge machining apparatus shown in FIG. 42 is the same as that shown in FIG. 42, except that the machining gap voltage fEg) between the two is different. In Fig. 42, the machining gap voltage fEg) between Torr, that is, between time 1 (T2) and time (T3), is kept at a high voltage, but in Fig. 2, after time (T2) , has rapidly decreased to zero. This is due to the stray capacitance (
This is because the charge stored in the resistor [17) is discharged through the resistor [1021]. Therefore, the 42nd example showing the conventional example
Compared to the figure, it is relatively rare for the average machining voltage to become abnormally high, which has the effect of stably controlling the machining gap.

Note that although FIG. 2 shows the case where voltage (E31 > voltage (E, l), the case is not limited to this; voltage (E3) ≦ voltage (El
).

Embodiment 2 Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a connection diagram of a discharge circuit showing another embodiment of the present invention. FIG. 3 shows a configuration in which a discharge interruption detection circuit for detecting interruption of discharge is added to FIG. 1.

Next, the discharge interruption voltage detection circuit will be explained with reference to FIG. In FIG. 3, (302) is a discharge interruption voltage detection circuit. Input terminal (30) of discharge interruption detection circuit (302)
2a) is connected to the output terminal (13c) of the differential amplifier (13), and the output terminal (302b) is connected to the input terminal (7d) of the oscillation circuit (7) and the one-shot multi-by-break (
15) is connected to the input terminal (15d).

Next, we will discuss the operation of the discharge interruption detection circuit (302+) in the fourth section.
This will be explained using the operation time chart shown in the figure. Usually, the voltage (El) of the first DC power supply (3) is the same as that of the third DC power supply (9).
Since the voltage (E3) is lower than the voltage (E3), the voltage (
A voltage (ESO) higher than the voltage (El) is set as the discrimination level. When the machining gap type EiEg) becomes a voltage higher than the second discrimination level 1EsO1, the discharge interruption detection circuit (302) is configured to output °゛1'' to the output terminal (302bl). Third
If the discharge is interrupted while voltage is being applied by the DC power supply (9) of the DC power source (9), a value of "1" is output to the output terminal +302b).The output terminal +30 of the discharge interruption detection circuit +302)
When "1" is output from 2b), the output of the output terminal (7a) of the 9 oscillator (7) is set to "o" up to T3, and the output of the output terminal f15b) of the one-shot multivibrator (15) is is set to "0" until the next trigger.

Therefore, between time point 7 (T1) and time point (T3), the oscillator (7
) and the output terminal (15c) of the one-shot multivibrator (15) both output 1", so the output terminal (104a) of the two-man power AND circuit (104) outputs "1". ' is output and the semiconductor switch 03) is turned on. When the semiconductor switch 03) is turned on, the charge stored in the stray capacitance (17) is discharged through the resistor 02), and the machining gap voltage (Egl) decreases to zero.

Also, this Example 2. Compared to Example 1, the abnormal increase in the average machining voltage can be further reduced, and the machining gap can be controlled more stably.

Embodiment 3 Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a connection diagram of a discharge circuit of an electric discharge machining apparatus showing this embodiment. Further, FIG. 5 shows a second DC power supply (502) provided in series with the resistor (102+) of the bypass circuit flol in FIG. Power supply +502), resistor 02), semiconductor switch (103).

A voltage holding means 1, for example, a reverse voltage application circuit (501) is configured from a two-manpower NAND circuit (104+).

FIG. 6 is an operation time chart of the discharge circuit shown in FIG. 5. This FIG. 6 is the same as the operation time chart shown in FIG. 2, except that the machining gap voltage iEg) while the semiconductor switch (6) and semiconductor switch (10) are off is different. That is, while the semiconductor switch (6) and the semiconductor switch (10) are off, the reverse voltage application circuit (machining gap voltage iEg by 5011) is applied with a polarity equal to or negative in magnitude to the output voltage of the second DC power supply f502+. The voltage (Vcl) is set.

In this case, the machining gap voltage (Egl) is used as is, without calculating the average machining voltage for controlling the machining gap, and for the period when the machining gap voltage (Eg) is a negative voltage, the machining gap voltage (Is it necessary to use it by rectifying it so that Egl becomes zero?

Furthermore, if the voltage of the second DC power supply (502) is set lower than the voltage at which discharge is possible, it is possible to prevent sustained arc discharge that is likely to occur due to discharge in the negative direction.

FIG. 7 is an operation time chart in the case where no interruption of 1'll electricity occurs for some reason during discharge. This FIG. 7 is the same as FIG. 6 except that the machining gap voltage [Eg] remains at a predetermined voltage (Vgl) between time point (T, l) and time point (T2).

Moreover, FIGS. 8 to 10 are explanatory diagrams showing the direction in which current flows in the zero release circuit shown in FIG. 5.

Arrow +8011 in Figure 8 is a semiconductor switch (6)
Indicates the direction in which current flows when the is on.

The arrow (901) in Figure 9 indicates the semiconductor switch is O)
Indicates the direction in which current flows when the is on.

The arrow EfN1001) in FIG. 10 indicates the direction in which current flows when the semiconductor switch (103) is on.

This Example 3. Example 1. In addition to having the same effect as shown in FIG. 7, in addition to the normal positive voltage, a negative voltage, which is the opposite voltage, is applied to the machining gap.
This has the effect of preventing deformation of the surface shape of the workpiece (2) due to electrolysis or electrolytic corrosion. It also has the effect of reducing the phenomenon in which the workpiece is magnetized.

Example 4 Next, as still another example of the present invention, Example 3
The case where the average machining gap voltage is set to 0■ by controlling the output voltage of the second DC power supply (5021) will be explained in detail. Fig. 11 is a connection diagram of the discharge circuit of the discharge machining apparatus showing this embodiment. In Fig. 11, +1101+ and (1102) are voltage dividing resistors, and (1103) is a capacitor.One end of the voltage dividing resistor (11011 is connected to the electrode fl), and the other end is the voltage dividing resistor. (1102).The other end of the 1 voltage dividing resistor +1102+ is connected to the workpiece (2).
The capacitor (103) is connected to the voltage dividing resistor (103).
1021 in parallel. (1105] is a differential amplifier, and the negative input terminal fl105a) of this differential amplifier (1105) is connected to the connection point of the voltage dividing resistor 101) and the voltage dividing resistor (1102), The other input terminal 105b) is connected to the workpiece (2). In addition, 7 voltage dividing resistor [1101), +110
21. The average machining gap voltage is detected by a capacitor (1103) and a differential amplifier (105).

+1107+ is a digital variable output voltage power supply.

This digital variable output power supply (1107) is a second DC power supply +5021 shown in FIG. 5 provided with a variable voltage mechanism (not shown) that outputs a predetermined voltage based on a digital input signal. [11061 indicates that the input terminal fl106a) is the output terminal 1 of the differential amplifier fl1051.
1105c), and this output terminal (1,105c
LO6bl is an interface circuit that outputs a predetermined digital signal output terminal (1106bl) based on the average machining gap voltage output to ) so that the average machining gap voltage becomes Ov. The control terminal (not shown) of the variable output power supply fl107) is manually operated.

Note that FIG. 11 shows the example 3. In Figure 5, which shows
A variable output voltage mechanism is provided in the second DC power supply (502),
The digital variable output voltage power supply is 107), and further,
Interface circuit (1106), voltage dividing resistor (1
101) 11102), capacitor fl103),
A differential amplifier (l105j) is provided. Also, a digital variable output voltage power supply (l105j) is provided.
71 variable output voltage mechanism (not shown) 1 voltage dividing resistor f
1101), fl102), capacitor is 103)
, a differential amplifier (mos), and an interface circuit (1106) constitute a voltage setter (jUfloo).

Section 12 is a connection diagram showing details of the interface circuit fl106). In the figure, +12011 is a voltage comparator, (1202+ is a clock pulse generator).

(1203+ is an n-bit up/down counter,
+1204) is an inverting circuit that inverts the input digital signal and outputs it, +1205) and (1206)
is a two-person AND circuit.

The positive input terminal of the voltage comparator 201) is the input terminal (l10) of the interface circuit (1106).
6al, the negative polarity input terminal +1201b of the voltage comparator (1201) is grounded, and the voltage comparator f120
11 output terminal (1201c) is a two-man power AND circuit 11
One input terminal of 205) is connected to 205a) and the input terminal 11204al of the inversion circuit (12041).The output terminal of the clock pulse generator f1202+ [
1202a) is the other input terminal (12 (15bl) of the two-man power AND circuit f12051 and the two-man power AND circuit (1
206) is connected to one input terminal f1206a). In addition, the 1 inverting circuit has 8 terminals f1204 of 204)
bl is connected to the other input terminal (1206bl) of the two-man power AND circuit (1206).
It is connected to the count-up input terminal (1203al) of the output terminal (1205cl is the up-down counter 11203) of the ND circuit +12051, and
2061 output terminal 11206c) is the countdown input terminal +1203 of up/down counter t12031
b) connected to.

+1207) is an initial setting value storage unit that stores an initial value to be set in the up/down counter +1203). This initial setting value storage unit (12071) has a storage capacity of n bits and has output terminals FM, i to fM, and l that output the stored binary information in parallel.These output terminals ( M, ) to (Mn) are data input terminals (Dl) of the up/down counter f1203+, respectively.
~fDnl. +12081 is a processing start pulse generator that outputs a processing start pulse to the output terminal (1208a) at the start of processing. The output terminal (1208a) of this processing start pulse generator +1208) is connected to the input terminal fLD+ of the up-down counter 203), and the above-mentioned processing start pulse is connected to the input terminal tLD) of the up-down counter (1203). When done manually,
The contents of the initial setting value record/national capital +12071 and the up/down counter are set to 203). In addition, the output terminals (Ql) to (S) of the up/down counter t12031 are connected to the voltage setting input terminals (Sl) to (S, ) of the digital variable voltage power supply +1107, respectively, and the output terminals (Ql) to (S) of the up/down counter t12031 are connected to the voltage setting input terminals (Sl) to (S, ) of the digital variable voltage power supply +1107), and The output voltage of the digital variable voltage power supply fl1071 is set.

Next, the operation of the interface circuit fl106) will be explained. First, when a machining start pulse is given from the machining start pulse generator (12081) to the input terminal (LD) of the up/down counter f12031 at the start of machining, the contents of the initial setting value storage unit t12071 are set in the up/down counter 203. Ru. Then, the digital variable voltage power supply fl107) outputs an output voltage based on the contents of the up/down counter 203). This output voltage is applied between the electrode (1) and the workpiece (2) when the semiconductor switch +103) is on.

On the other hand, the voltage between the electrode (1) and the workpiece (2) is divided by the voltage dividing resistor (1101), fl102) (the voltage dividing resistor (1103+) and the voltage dividing resistor +11).
011.1l102) is integrated by an integrating circuit configured by

The average machining gap voltage is output to the output terminal (1105cl) of the differential amplifier (1105).This average machining gap voltage is used as a feedback signal to output the positive polarity of the voltage comparator (1201+) through the input terminal 11106a) of the interface circuit 106). The target average machining gap voltage value Ov is input to the input terminal (1201a) of the voltage comparator circuit 201.
)'s negative polarity input terminal (1201bl).

If the average machining gap voltage is a positive voltage, the voltage comparator (12
The output terminal (1201c) of 011 outputs "■", and if the average machining gap voltage is a negative voltage, the output terminal (1201c) outputs "■".
1c) outputs "0". Clock generator (1202
+ always generates a pulse with a predetermined period, and when the output terminal 11201c) of the voltage comparator 201) is "1",
That is, when the average machining gap voltage is a positive voltage, the output terminal [1205c] of the two-man power AND circuit (1205) is connected to the output terminal 11202 of the clock pulse generator +12021.
A pulse having a waveform similar to that in a) is output, and the up/down counter +tzol counts up. Also,
When the output terminal (1201c) of the voltage comparator 201) is 0゛.

In other words, when the average machining gap voltage is negative, two-man power AND
The output terminal of the circuit f12051 (1205cl becomes "0", and the output terminal f120 of the 1 inverting circuit +1204+
4b) becomes "1", and the clock pulse generator outputs a pulse having the same waveform as the output terminal 11202a) of 202) to the output terminal f1206c) of the two-man power AND circuit f12061, and the up/down counter 203 ) counts down. Therefore, the up/down counter 1 is set to a value such that the average machining gap voltage becomes Ov.
The contents of 1203+ are automatically set. The digital variable voltage power supply +1107 outputs a voltage based on the contents of the up-down counter (1203), and this voltage is output as a negative voltage to the machining gap while the semiconductor switch +1031 is on. This makes the average machining gap voltage Ov.

FIG. 13 is an operation time chart showing how the up/down counter 203) operates as the average machining gap voltage changes. In the ward, Figure 13 (
a) is a machining signal that is Pa 0” before the start of machining and becomes 1 Pa after the start of machining, and tb+ in Figure 13 is the clock pulse generator +
The waveform of the output terminal (1202a) of 1202), Figure 13 ic) is the output terminal 11105 of the differential amplifier +1105+.
The waveform shown in c) shows the average machining gap voltage. In Figure 13 fd), the voltage comparator is the output terminal (12) of the voltage comparator 201).
01c). In Fig. 13(e), the count up input terminal of the up/down counter f1203) is 20.
3a), the countdown input terminal 203b) in FIG. 13, and the waveform in FIG.

Clock pulse generator +12 as shown in FIG.
02+ applies a pulse of a predetermined period, and when the average machining gap voltage is a positive voltage, the voltage comparator (output terminal f1201c of 12011) becomes "1pa," and when it is a negative voltage, it becomes 0.
”.The output terminal of the voltage comparator +1201+ (
1201c) is 1'', the clock pulse generator 11
The pulse of the output terminal (1202a) of the up/down counter 11203) is applied to the count up input terminal (1203al) of the up/down counter 11203), and the pulse is applied to the output terminal (1201c) of the up/down counter 11203).
When is “0”, clock pulse generator f1202
The pulse of the + output terminal f1202a) is the countdown input terminal +1203 of the up/down counter f120]
b) is applied. Therefore, the up/down counter [1
2031 counts up when the average machining gap voltage is a positive voltage, and counts down when it is a negative voltage.

FIG. 14 is a diagram showing signal waveforms of the main parts of FIG. 11. Example 1. In Figure 2, which shows 9 time points (T2)
The voltage fa in FIG.
The waveform approaches VC+. Regarding other waveforms, FIG. 14 is the same as FIG. 2.

FIG. 15 is a diagram showing signal waveforms of the main parts of FIG. 11 when discharge is not interrupted. This Fig. 15 shows the machining gap voltage (Eg) (at is the time (T1)
and time (T2), the voltage does not rise and maintains the same voltage as before time (T1), and after 1 o'clock, t3iT21, it approaches a negative predetermined voltage (waveform). Also, the discharge current (1g) FIG. 15 th+ shown in FIG. 15 is the same as FIG. 14 except that the current value increases toward zero at time fT, ) until time T2.

In this embodiment 4, the average machining gap voltage is controlled to be O■, so that the effect of embodiment 3 can be more fully obtained.

Embodiment 5 Next, as still another embodiment of the present invention, a case will be described with reference to FIG. 2 in which the average machining gap voltage is set to O■ by controlling the time width during which the semiconductor switch f103+ is turned on. FIG. 16 is a connection diagram of the discharge circuit of the discharge machining apparatus in this case.

Figure 16 shows the two-man power AND circuit (104
) output terminal (104al and semiconductor switch +1031
A variable pulse width one-shot multi-by-break f1601) is provided between the control terminals (103a) of the control terminal (103a), and as in FIG.
, the capacitor tllO], and the differential amplifier is 1
05) is provided, and the output terminal (l105c) of this differential amplifier +11051 is connected to the pulse or width control terminal (1601c) of the variable pulse width multi-by-break (1601).
It is designed to connect to l. In other words, the output terminal 1104al of the two-man power AND circuit f1.041 is a variable pulse width one shot multi-by-break 601)
Connected to the trigger terminal (1601a) of the variable pulse width one-shot multi-by-break+1601+ output terminal! 1601b+ is connected to the control terminal 1103a) of the semiconductor switch f103).

Note that 7 voltage dividing resistors + 110L), (11021, capacitor fl1031, differential amplifier fl105), and variable pulse width one-shot multivibrator f
16011 constitutes a voltage application time setting means [1600].

FIG. 17 is a detailed connection diagram of the variable pulse width one-shot multi-by-break f16[)l). FIG. 17 shows Example 4. In the interface circuit (1106), a capacitor (17011, a resistor (17021, flip-flop +1703), a two-person OR circuit +1704+
, (1705+.

2-person AND circuit 11710), counter 706)
, -number comparison circuit f1707), and maximum value comparison circuit (17081), and the two-man power AND circuit is 2051!In addition, the maximum value comparison circuit described above +170
．． Add an input terminal to input the output signal from 91,
This is a human-powered AND circuit f1709].

Variable pulse width one-shot multivibrator (160
The trigger input terminal of 1) is 601a) and the capacitor (17
01), and the other end of the capacitor 701) is a flip-flop (S input terminal of 17031 is connected to 703).
a) and one end of resistor +1702), and the other end of resistor (1702) is grounded. Also, the N output terminal (1703b') of the flip-flop (1703)
is one input terminal (1) of the two-person AND circuit (1710)
710a) and a variable pulse width one-shot multi-by-break (16011).

The other input terminal (17) of the two-person AND circuit (1710)
1ob) is connected to the output terminal (1202a) of the clock pulse generator 202), and the two-man power AND circuit (171)
0) output terminal f1710c) is a counter (1706)
is connected to the count input terminal f1706a).

The output terminals (Pl) to (P, ] of the counter 706) are respectively connected to one comparison input terminal (80) to fAn) of the coincidence comparison circuit (1707).

On the other hand, the comparison input terminals (B1) to (Bo) are the output terminals (Ql) to (Q) of the up/down counter 203, respectively.
,, connected to l. - Number comparison circuit (matching ratio terminal (1707a) of 17071 is a two-man OR circuit t170
4) One of the input terminals (1704al and 2 manual O
It is connected to the R circuit (one input terminal (1705a) of the 17051; the other input terminal (1704b) of the two-person OR circuit +1704+) and the two-person OR circuit [
The other input terminal +1705b) of the processing start pulse generator 1705) is connected to the output terminal (1208a) of the processing start pulse generator 208). Furthermore, two-person OR circuit (1704)
The output terminal (1704c) of the flip-flop (170
Connected to R input terminal (1703c) of 3+, 2-man power O
It is connected to the R circuit (reset input terminal f1706b of the output terminal of 17051 (1705cl is the counter 706)). One of the comparison input terminals (Ul) to (U, , ) of the maximum value comparison circuit (17081) is connected to the output terminals (Patch) to (S) of the up/down counter 203, respectively, and the other comparison input terminal (Vl ) to +V, ) are the output terminals (Ml) to f of the initial setting value storage unit [1207], respectively.
M,).

In addition, the output terminal f170 of the maximum value comparison circuit f1708)
8a) outputs 1゛ when the data of one comparison input terminal (Ul) to (shi.) is smaller than the data of the other comparison input terminal (Vl) to +V, , and outputs 0゛ when it is larger. do. In addition, this output terminal f1708a) is
It is connected to the input terminal f1709d+ of the ND circuit (171) 91. In addition, a three-person AND circuit (1709)
The other input terminals (1709a), f1709bl and output terminals [1709c) are connected to the 12th terminal, respectively.
The input terminal of the two-person AND circuit (1205) in the figure (
1205a), (1205b) and the output terminal is 2
This is the same as the connection destination in 05c).

Next, the operation of the variable pulse one-shot multi-by-break f160L+ shown in FIG. 17 will be explained.

First, at the start of machining, the machining start pulse generator (1208)
The processing start pulse is increased by the up/down counter (1203
), the initial setting value
The contents of the mold section (1207) are up/down counter (12
03). Note that the initial setting value storage unit (12
07), the up/down counter 1120 is set in advance.
Since the count upper limit value of 3) is set, the up/down counter +12031 is set to the count upper limit value at the start of machining. Further, at this time, the counter (1706) and the flip-flop (17031 is a two-man OR circuit f1705) are reset simultaneously via the f1704+.

On the other hand, the semiconductor switch (6) and the semiconductor switch (
10) are both turned off, that is.

When the output terminal (7c) of the oscillation circuit (7) and the output terminal (15cl) of the one-shot multivibrator (15) both change to 1°, two-man AND circuit (10
41 output terminal (104al).

This output terminal (104a) is the trigger input terminal (1
601al. In addition, a capacitor (1
7011 and the resistor [1702+], the output terminal (
104a) changes from “o” to “1”, a pulse is sent to the S input terminal (1
703a) and the flip-flop (17031) is set. When the flip-flop [1703] is set, the N output terminal t1703bl becomes "1",
The counter (17
A pulse similar to the pulse of the output terminal 11202a of the clock pulse generator (1202) is applied to the counter input terminal (1706a) of the clock pulse generator (1202). This pulse causes
The counter (1706) that has been reset in advance starts counting. Updown counter +1203
) and the counter (17061) match, "1" is output to the output terminal (1707a) of the match comparison circuit +17071, and the flip-flop f1703) is set to 2.
At the same time, the counter f1706 is reset via the manual OR circuit +17041, and the counter f1706 is reset via the manual OR circuit (1705).
Reset via. Therefore, the flip-flop (1
Variable pulse width one-shot multi-by-break f160 connected to N output terminal +1703b) of 703)
The output terminal 11601b) of 1) has an input terminal f160.
A pulse is output which rises at the same time as the signal inputted in 1a) and falls after a time based on the contents set in the up/down counter (12031).

Also, the output terminal of the differential amplifier +1105+ (1,105
c) is connected to the pulse width control terminal 601c), so 1. For example, if the average machining gap voltage is a negative voltage, the output terminal of the voltage comparator +12011 (1201cl is "0")
become. When the output terminal f1201cl becomes 0'', a pulse similar to the pulse at the output terminal of the clock pulse generator [1202] is applied to the countdown input terminal 203bl of the up/down counter f1203) through the two-man power AND circuit (1210+), and the countdown input terminal of the up/down counter f1203) is applied to the up/down counter f1203). Down counter (
1203+ counts down. When the up/down counter t1203) counts down, the width of the pulse output to the output terminal (1601b+) of the variable pulse width one-shot multivibrator (1601+ becomes narrow), and the pulse width is applied to the machining gap via the semiconductor switch (10:3). The time for applying a negative voltage decreases, increasing the average machining gap voltage.When the average machining gap voltage increases and becomes a positive voltage, the output terminal f1708a of the maximum value comparison circuit +17081
) is P1"°, a three-person AND circuit f1709
), the pulses of the clock pulse generator (1202) are applied to the up-down +1203+ count-up manual power, and the up-down counter (1203) counts up, causing the average machining gap voltage to decrease. Therefore.

The output terminal of the maximum value comparison circuit +1708+ is the up/down counter +1 when 708a) is °1''.
The content of 2031 is a value that makes the average machining gap voltage o■. In addition, when the contents of the up-down counter f12031 become equal to the contents of the initial setting value storage section +12071, even if the average machining gap voltage is a positive voltage, the up-down counter (1203+ does not count up and the up-down counter The content cannot be thicker than that.

Note that the reason why the contents of this up/down counter [12031 are limited so that it does not exceed the value set in the initial setting value storage section (1207) is that the output terminal +1601b of the variable pulse width one-shot multivibrator (1601) This is to prevent the pulse width of ) from exceeding the discharge pause time (the time during which both the semiconductor switch (6) and the semiconductor switch f10+ are off).

Figure 18 is a time chart showing how the up-down counter (12o3+) operates as the average machining gap power changes. While the output terminal of the comparator circuit 11708] (in addition to adding the waveform fddl of 1708a+, this waveform 1dd) is 0'', the waveform fe of the count-up input terminal f1203al of the up-down counter is also “
It has become °0゛. Therefore, during this period, the up-down counter (1203j wave sweat? fgl has a waveform in which the count-up is stopped.
〜(dl, ffl are respectively shown in FIG. 13(al〜
This waveform is similar to +a+ and +f+.

FIG. 19 is an operation time chart in the case where no interruption of discharge occurs. FIG. 19(b) to th+ are
Example 4, respectively. This is similar to FIG. 15, tb+ to thl. In addition, Fig. 19 (if is the output terminal of variable pulse width one-shot multi-by-break (16011)
1601b+ waveform is shown. Also.

Figure 19 fat showing the machining gap voltage is the output terminal (16
01b) is '1'', the waveform is such that a predetermined negative voltage is applied.

Note that this Example 5. Accordingly, the same effect as in Example 4 can be obtained.

Embodiment 6 Next, as still another embodiment of the present invention, a case in which the average machining gap voltage is set to Ov by controlling the discharge pause time will be described with reference to the drawings.

FIG. 20 is a connection diagram of a discharge circuit of an electric discharge machining apparatus showing this embodiment. This FIG. 20 shows Embodiment 3 of this invention.
．． Figure 5 shows the voltage dividing resistor (1101), +110
2) , capacitor +11031, differential amplifier +11
05], and interface circuit +20011
A discharge pause time setting means +20001 is provided. In addition, the differential amplifier (13)
The output terminal of is connected to the input terminal f2001a) of the interface circuit f2001), and the output terminal of the interface circuit 12001+ is connected to the setting input terminal of the off-time setter +4011) of the oscillation circuit (7).

In addition, both the setting input terminal of the off-time setting device +4011+ and the output terminal of the interface circuit (2001) are connected to the off-time setting device +401 of the oscillation circuit (7), respectively.
There are the same number of output terminals as 1+ output terminals, and digits of the same - order are connected to each other.

FIG. 21 is a connection diagram of the interface circuit +2001). FIG. 21 shows Example 4. Compared with FIG. 12 showing the interface circuit (1106) in
They are the same except that the connection destination is different. That is, in Fig. 12, the output terminals (Q- to fQn) of the up/down counter +1203) are connected to the digital variable output voltage power supply (1107), but in Fig. 21, the oscillation circuit (7) is turned off. It serves as a setting input terminal for the time setting device 14011).

Next, the operation will be explained. Applying a voltage of opposite polarity to the machining gap during the discharge pause time is the same as in Example 3, but as described above, in order to control the average machining gap voltage to Ov, an interface circuit (20011) is provided. The operation of this interface circuit (2001) is controlled by the magnitude of the negative voltage applied to the machining gap in Fig. 12, but in Fig. 21 it is the discharge pause time. The same is true.

Further, FIG. 22 is an operation time chart of the interface circuit +2001+. FIG. 22 shows Example 4. This is similar to FIG. 13 which shows.

FIG. 23 shows this Example 6. This is an operation time chart. Note that this operation time chart is for the case where no interruption of discharge occurs. 8. FIG. 23 shows Example 4. Compared to the operation time chart of FIG. 15, the discharge pause time (Tk) is different, but other aspects are the same. Also, this Example 6. The effect of Example 4 is also observed.
It is similar to

Embodiment 7 Next, as still another embodiment of the present invention, a case where the average machining gap voltage is set to Ov by controlling the time during which a positive voltage is applied to the machining gap will be described with reference to the drawings.

FIG. 24 is a connection diagram of a discharge circuit of an electric discharge machining apparatus showing this embodiment. FIG. 24 shows Example 6. They are the same as FIG. 20 except that the connection destination of the output terminal of the interface circuit +20011 is different, and the interface circuit +2001+ is replaced with the interface circuit +24011. Namely.

In FIG. 20, the interface circuit (2001
) is connected to the setting input terminal of the off-time setter +4011) of the oscillation circuit (7), but in Fig. 24, the on-time setter (4010) of the oscillation circuit (7)
) is the setting input terminal. Also, 9 resistors for voltage division +
1101+, tl1021, capacitor fl103)
, differential amplifier f11051, and discharge voltage application time setting means +24 from the interface circuit (2401)
001 is configured.

FIG. 25 is a detailed connection diagram of the interface circuit t24011. This FIG. 25 shows Example 5. Compared to FIG. 17, which shows the interface circuit of +1601).

Output terminal (Ql) of up/down counter f1203+
The connection destination of ~(shi) is the setting input terminal of the on-time setting device +4010+ of the oscillation circuit (7), and the capacitor is 70
11, Resistor (17021, Flip-flop (170
3], 2-person OR circuit f1704+, 2-person OR circuit (17051, counter +1706+, - number comparison circuit (1707), and maximum value comparison circuit +1708+
is excluded, and the 3-man power AND circuit f17091 becomes the 2-man power A
Although it is an ND circuit 112051, the other components are the same.

Moreover, FIG. 26 is an operation time chart of the interface circuit (24011).
The reason why the polarity of the machining gap voltage (Eg) shown in FIG. 18 and the machining gap voltage (Eg) shown in FIG. 5
．． For example, if the average machining gap voltage is a positive voltage, it is necessary to count up the up/down counter f1203) and increase the time for applying a negative voltage to the machining gap to decrease the average machining gap voltage. For,
In this embodiment 7, if the average machining gap voltage is a positive voltage, it is necessary to count down the up/down counter 11203) and reduce the time for applying a positive voltage to the machining gap to reduce the average gap voltage. This is because there is. The reason why the maximum value comparison circuit f1708) is provided in the interface circuit +24011 is that if the time during which a positive voltage is applied to the machining gap is increased indefinitely, the discharge may not occur normally.

Also, the operation of the interface circuit +2401) is as follows.

This embodiment is the same as the interface circuit (2001) of the sixth embodiment, except that the maximum value comparison circuit (1708) limits the count up as in the fifth embodiment, so a detailed explanation will be omitted.

FIG. 27 is an operation time chart of the discharge circuit shown in FIG. 24. This FIG. 27 shows the example 3. Fig. 27 fb) and Fig. 7 fbl, which show the state of the control terminal of the semiconductor switch (6), are different from Fig. 7, which shows the state of the control terminal of the semiconductor switch (6). That is, in Figure 7, Figure 7 ib) is "L
'', which is the time during which the semiconductor switch (6) is on, is constant, but is variable in FIG. 27(b).

In addition, in FIG. 27, the one-shot multi-by-break (15) is not triggered between the first time point fT2701+ and the time point (T2702), and after the pulse is output to the output terminal (7b) of the 9th oscillation circuit (7), the first DC power supply (3
) is illustrated. In addition,
Other than the above-mentioned differences, FIG. 27 is the same as FIG. 7.

FIG. 28 is an operation time chart of the discharge circuit shown in FIG. 24 when no discharge occurs. In the figure,
FIG. 28 shows the voltage waveform of the control terminal 1103a) of the semiconductor switch t1031 (cl is the semiconductor switch (6)
Fig. 28 (b) shows the state of the control terminal (inverted signal of bl).
When it is 1", it becomes the voltage of DC power supply (3) of set 1, and it is "0"
At this time, the voltage is negative due to the second DC power supply (502). FIG. 28(d) shows the waveform of the output terminal (7b) of the oscillation circuit (7), and is similar to FIG.

In addition, FIG. 28(e) shows the voltage waveform of the output terminal +14b) of the discharge detection circuit (14), FIG. 28(f) shows the voltage waveform of the input terminal 1L5a) of the one-shot multivibrator (15), and FIG. 28(g) showing the voltage waveform of the control terminal of the switch (10) and FIG. 28(h) showing the discharge current waveform both remain at OV.

Note that FIG. 28 shows how the average machining gap voltage is controlled to Ov even when no discharge is performed.

Moreover, the effect of this Example 7 is similar to that of Example 4. It is similar to

In addition, Example 7. In Figure 27, Fbl is "1"
27 (from the rising edge of the waveform in bl to the rising edge of the waveform in FIG. Figure 27: 27th rise of fd+ waveform
A similar effect can be obtained by making the time until the fall of the waveform of bl constant.

Also, Example 4. ~Example 7. , any one of the output voltage of the second DC power supply (502), the time for applying a reverse voltage to the machining gap, the discharge pause time, and the time for applying a positive voltage to the machining gap is variable. You may also do so. For example, Example 4. ~ When implementing any of Example 7゜, there is a limit to the variable range of the parameter to be changed in order to control the average machining gap voltage to 0■, and the average machining gap voltage is OV.
There are some things that cannot be done. In such a case, any of the above-mentioned identification parameters may be automatically changed to control the average machining gap voltage to Ov.

Example 9 Furthermore, Example 3. ~Example 8. resistor +10 at
2+ may have a high resistance, and the output voltage of the second DC power supply +5021 may be set to a high voltage capable of discharging.

FIG. 29 is an explanatory diagram illustrating the machining gap voltage and discharge current when the output voltage of the second DC power supply (502) is high and when the resistance value of the resistor +102) is large and small, respectively. be.

Figure 29 (al and +bl are resistors (102
) are the machining gap voltage and discharge current when the resistance value of resistor +1021 is small, and FIG. 29 fcl' and Tdl respectively show the machining gap voltage and discharge current when the resistance value of resistor +1021 is large. Figure 29 fa) is time +T2901
1 to time f72902) is a high negative voltage as a no-load time, and then discharge starts and becomes a low negative voltage +E2901), and tb+ in Figure 29 shows the waveform from time fT2902) to time fT29031. while,
A large negative current 1i2901) momentarily flows because the charge stored in the stray capacitance in the machining gap is discharged.

After that, the waveform is such that a sustained arc current (i2902) flows. FIG. 29 icl is a high negative voltage as the no-load time from time point (72904+ to time point (T2905+), and from time point 9 [T29051 to time point (T29061)
In.

A discharge occurs instantaneously, and a low negative voltage (E2901
), but the waveform immediately returns to a high negative voltage. Also, at the 2-point fT29071, the semiconductor switch [
103) is turned off and returns to Ov.

Figure 29(d) shows the time point (T2905) and the time point +29
At 061, the charge stored in the stray capacitance in the machining gap is discharged, resulting in a waveform in which a large negative current momentarily flows.

That is, as shown in FIGS. 29(a) and 29(b), the resistor f102+ is set to the same value as the current limiting resistor (5), and the output voltage of the second DC power supply (502+) is set to the same value as the current limiting resistor (5).
When the output voltage (El) of the DC power supply (3) is set to about
Discharge in the negative direction tends to become a connective arc discharge. On the other hand, as shown in Fig. 29 fc) and fd), if the resistance value of the resistor f102) is increased to about 20 to 100Ω, the discharge current becomes unsustainable and is stored in the stray capacitance in the machining gap. The discharge current is only due to the electric charge present.

Therefore, even if a high negative voltage is applied to the machining gap,
Since the negative discharge current hardly flows, the workpiece (2)
It is possible to control the average machining gap voltage without causing damage.

Embodiment 10 Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 30 shows Example 3. In Fig. 5, which shows a discharge diagram, an example is shown in which the output of the first DC power supply (3) is supplied to the machining gap with either positive or reverse polarity, and the second DC power supply (f5021) is not required. It is a connection diagram of the discharge circuit of a processing device.

That is, in FIG. 30, the semiconductor switch (6) is turned on and off together with the semiconductor switch (6) in FIG.
A first semiconductor switch that connects or disconnects the force to the machining gap with positive polarity, and a second semiconductor that turns on and off together with the semiconductor switch +103) and connects or disconnects the output of the first DC power supply (3) to the machining gap with opposite polarity. Install a switch 1
When the output terminal (7a) of the oscillation circuit (7) is 1p, the output of the first direct power source (3) is applied to the machining gap with positive polarity,
When the two-man power AND circuit (pressure terminal f104a of 1041) is 1'', the pressure of the first DC power supply (3) is connected to the machining gap with the opposite polarity, and the second DC power supply (f502) is connected. is made unnecessary.

In FIG. 30, (30011 is the first semiconductor switch, (30021 is the second semiconductor switch). The first semiconductor switch f30011 is the anode of the diode (4) and the electrode (1) of FIG. The anode of the first semiconductor switch +30011 is connected to the electrode il+, and the cathode is connected to the anode of the diode (4).The control terminal of the first semiconductor switch +3001) is connected to the oscillation circuit ( 7) is connected to the output terminal (7a).

In addition, in Fig. 5, the resistor (one end of 102+ is connected to the second
is connected to the cathode of the DC power supply f502+, but the third
In Figure 0, it is connected to the cathode of the first DC power source (3) instead of the second DC power source (502). moreover,
The anode of the second semiconductor switch (3002) is connected to the anode of the first DC power supply (3), and the second semiconductor switch f
The cathode of 3002) is connected to the electrode). Also,
The control terminal of the second semiconductor switch +3002+ is connected to the output terminal f104al of the two-man power AND circuit (104). Note that other connections in FIG. 30 are the same as in FIG. 5.

Also, a first semiconductor switch (3001), a second semiconductor switch +3002+, a semiconductor switch 1103
1 and 2 manual AND circuits + 1041 constitute a changeover switch circuit (3000).

Next, the operation will be explained using the operation time chart shown in FIG. 31. FIG. 31 shows the machining gap voltage fEg) during the discharge pause time in Example 3. This is different from FIG. 7 which shows the above, but other aspects are the same as FIG. 7. That is, the 31st
Figure (a) shows the time point F in Figure 29 fc) showing Example 9 between time point tT3101+ and time point fT31021.
T2904) to time tT290? The waveform is similar to the + waveform. 32 to 34 show when the semiconductor switch (6) and the first semiconductor switch (3001) are on, and when the semiconductor switch (10) is on, respectively, in FIG. 30. , a semiconductor switch (103), and a second semiconductor switch (300)
2) is an explanatory diagram showing the direction of the current flowing in the discharge circuit when it is on.

In other words, until the discharge starts, the arrow +32 in Fig. 32
The current flows in the direction shown by 011, and when the discharge starts, the current flows in the direction shown by the arrow (3301) in FIG. The machining gap voltage is applied in a flowing manner.

In FIG. 30, one end of the resistor f102+ is connected to the cathode of the first DC power supply (3), or may be connected to the anode of the diode (4). Furthermore, the resistor 11021 is connected to the first DC power supply (3
) and the cathode of the semiconductor switch (103+), but the semiconductor switch (103) is not limited to this.
For example, it may be inserted between the anode of the first DC power supply (3) and the anode of the second semiconductor switch +30021.

This Example 10 is similar to Example 3. It has the same effect as that, and also does not require a second DC power supply, so
This has the effect that the discharge circuit can be constructed at low cost.

Also, Example 5. ~Example 8. In Example 10.
Similarly, the second DC power supply F5021 may be made unnecessary. In this case, both Example 10. The same effect can be obtained.

1 above the blood plexus Furthermore, Example 3. ~Example 11. In.

Example 2. Similarly, a discharge interruption detection circuit (301) may be provided to apply a voltage of opposite polarity to the machining gap immediately upon interruption of the discharge. In this case, both Example 2. It has the same effect as , or is additionally added.

Embodiment 13 FIG. 35 is a connection diagram of the discharge circuit section of an electrical discharge machining apparatus showing still another embodiment of the present invention. This figure 35 is
As a conventional example, a bypass circuit (3500) is provided in the discharge circuit shown in FIG.

Next, the 2 bypass circuit +35001 will be explained.

In the figure, +3501+ is a resistor, (350
2) is a semiconductor switch, and a series resistor (35011 and semiconductor switch f35021 is connected between the electrode (1) and the workpiece (2). +3503) is an inverting circuit, and this inverting circuit +3503) output terminal (3
503b) is connected to the control terminal of the semiconductor switch 13502), and the input terminal (3503al) is the oscillation circuit (7).
is connected to the output terminal (7a) of.

In addition, the above-mentioned bypass circuit (3500) includes a resistor (35
01), a semiconductor switch +3502+, and an inverting circuit (3503).

Next, the operation will be explained using the operation time chart shown in Section 36. Fig. 36 shows a conventional example except that the machining gap voltage (Eg) differs between the discharge rest time, that is, the time point 9+T44021 and the time point (T4403).
Same as the figure. In Figure 36, 2 points 1T440
From 2), the machining gap voltage (Eg) has a waveform that rapidly decreases. time fT4402], the machining gap voltage (
The reason for the rapid decline in Eg) is at time 9 (T4402+
and time fT4403), the semiconductor switch (3502
) is conductive, and the charge stored in the stray capacitance (43051) between the electrode and the workpiece (2) is discharged via the resistor (3501).
In Example 1. Although it has the same effect as in Example 1, the processing speed is lower than that in Example 1 because it does not have the third DC power source (9).
．． In some cases, it is slower than .

Embodiment 14 - FIG. 37 is a connection diagram of a discharge circuit section of an electrical discharge machining apparatus showing still another embodiment of the present invention. This figure 37 is
In the 35th section showing Example 13, there is a voltage dividing resistor fil),
(12+, differential amplifier amplifier (13+).

Discharge detection circuit t14+, and discharge interruption detection circuit (3
700). In FIG. 37, the discharge detection circuit section comprising 7 voltage dividing resistors +11+, +12+, a differential amplifier (13), and a discharge detection circuit (14) is the same as that in FIG. 39 showing the conventional example.

Next, regarding the discharge interruption detection circuit (37001, the 37th
This will be explained using figures. (37011 is a flip-flop,
(3702) is a no-load detection circuit, (3703)
is a two-person AND circuit. flip flop +370
11 S input terminal 13701a) is a discharge detection circuit (1
4) is connected to the output terminal (14b) of R input terminal 13.
701b+ is connected to the output terminal (7c) of the oscillation circuit (7). In addition.

The output terminal (7C) is a terminal to which the inverted signal of the output terminal (7a) is applied. Output terminal f of differential amplifier (13)
13c) is the input terminal (3) of the no-load detection circuit (3702).
702a), and the output terminal (3702b) of the no-load detection circuit +37021 is connected to the two-man power AND circuit +3703.
It is connected to one input terminal (3703a) of 1.

Further, the other input terminal +3703b) of the two-man power AND garden path +3703+ is connected to the N output terminal 13701c) of the flip-flop f37011. Furthermore, the output terminal f3703c) of the two-man power AND circuit 13703+ is connected to the reset terminal (7d) of the oscillation circuit (7). Note that the signal at the output terminal (7a) of the 9 oscillation circuit (7) is a pulse that rises at a predetermined period and has a predetermined pulse width, or is output to the reset terminal (7d) when the output terminal (7a) is 1''. "When a 1P signal is input, the output terminal (7a) becomes 0 from then on until the 9th rising point",
The above-mentioned pulse width becomes narrower by that period.

Next, regarding the operation of the discharge interruption detection circuit (37001).

This will be explained using the operation time chart shown in FIG.

Figure 38 is Figure 45 showing the conventional example and time point (T4501)
to time fT4403) are the same. Time point (T
4501), when the discharge is interrupted, "1P" is output to the output terminal +3702b) of the no-load detection circuit f3702].

2-person AND circuit (one input terminal of 3703+ (37
03al becomes l". In addition, the no-load detection circuit +370
21 is.

The machining gap voltage fEg) is the machining gap voltage fVg during electric discharge.
) and the output voltage (E3510) of the DC power supply f4301), when it becomes larger than the predetermined voltage tE, 3801),
Output l゛ to output terminal +3702b), E, 380
It is configured to output ``1'' when it is smaller than 1.

On the other hand, the flip-flop +3701+ is at the time (T380
The discharge detection circuit (14) detects discharge in 1), and the output terminal of the discharge steering circuit (14) is set when the output terminal 4b) becomes "1", and the flip-flop (3701)
1's N output terminal f3701c) is set to "1"'. Therefore, the output terminal (3) of the no-load detection circuit (37021
When 702bl becomes 'l', two-man AND circuit +370
“1” is output to the output terminal (3703c) of 31. When “1” is output to the output terminal (3703c), “1” is input to the reset terminal (7d) of the oscillation circuit (7), causing one oscillation. The output terminal (7a) of the circuit (7) is changed from "l" to "Opa". Therefore, at time point fT4501) at 7, the semiconductor switch f4302) is turned off, and the semiconductor switch +3502+ is turned on, so that the semiconductor switch +3502+ is turned on and is stored in the machining gap. The charge that was present is discharged through resistor +35011,
1 time point fT4501 as shown in Figure 38 fa)
), the machining gap voltage fEg), which once started to rise, immediately decreases. Also, at the 7th point fT4501), the departure/return route (7)
When the output terminal (7a) of the flip-flop +37011 changes from '°1°' to '0', the output terminal (7C) changes from '0' to 'l', so the R input terminal (37
“1” is input to the flip-flop (37
01) is reset.

Also, at one point in time (T4501), the semiconductor switch +4302
) is turned off, both the output terminal F14b) of the discharge detection circuit (14) shown in Fig. 38 fc) and the output terminal (3702b) of the no-load detection circuit +3702) shown in Fig. 38E are The discharge current waveform (if) in FIG. 38 changes to zero.

In addition, during the no-load time between time 9 1T4401) and time fT3801), the flip-flop +37011
is not set, so the no-load detection circuit (3
Even if it is "1", the output terminal 13702b) of 702) or the output terminal 13703c of 2-man power AND circuit + 3703)
) remains at 0'' and does not reset the 9 oscillation circuit (7).

This Example 14. Regarding odor, since the third DC power source (9) is not provided, the processing speed may be slowed down, but the effect is similar to that of Example 2.

1 JL 2 knees Also, Example 3. ~Example 12. In.

Example 13. Or, as in Example 14, the third DC power supply (9), the diode (8), and the semiconductor switch are 0.
), One Shot Multivibrator (15).

The circuit for applying the output of the third DC power supply (9) constituted by the two-man power AND circuit (16) to the machining gap may be omitted.

In this case, since the third DC power supply (9) is not used, the rise of the discharge current may be delayed and the machining speed may be slowed down, but other aspects are the same as before omitting the third DC power supply (9). There is an effect.

Example 16゜In addition, Example 2. and Example 12. In the discharge interruption detection circuit +302), the machining gap voltage (Eg) is ESO
Whether or not it is determined that the discharge is interrupted when the voltage becomes higher is not limited to this.For example, Example 13. The discharge interruption detection circuit +37001 in the discharge interruption detection circuit (
It may be used instead of 302+. In this case, the relationship between voltage (El) and voltage (E3) is voltage tE, +
<It does not have to be limited to voltage (E3).

[Effects of the Invention] This invention is configured as described above, and even if a phenomenon of discharge or interruption occurs while applying voltage to the machining gap, the average machining voltage is maintained normally, so that the machining gap is It has the effect of stable control, properly protecting the electrode, and enabling high-precision, high-speed machining.

[Brief explanation of the drawing]

FIG. 1 shows Embodiment 1 of this invention. 2 is an operation time chart of the discharge circuit shown in FIG. 1, and FIG. 3 is a connection diagram of the discharge circuit of the electrical discharge machining apparatus. Example 2 of this invention. FIG. 4 is an operation time chart of the discharge circuit shown in FIG. 3, and FIG. 5 is a connection diagram of the discharge circuit of the electric discharge machining apparatus shown in FIG. 6 and 7 are operation time charts of the discharge circuit shown in FIG. 5, and FIG.
9 and 10 are explanatory diagrams showing the current path of the discharge circuit shown in FIG. 5, and FIG. 11 is an explanatory diagram showing the current path of the discharge circuit shown in FIG. Fig. 12 is a connection diagram of the electrical discharge circuit of the electrical discharge machining equipment.
Detailed connection diagram of the interface circuit shown in Figure 1, No. 13
12 shows an operation time chart of the interface circuit shown in FIG. 12, FIGS. 14 and 15 show an operation time chart of the discharge circuit shown in FIG. 11, and FIG. 16 shows a fifth embodiment of the present invention. 17 is a detailed explanatory diagram of the interface circuit shown in FIG. 16, FIG. 18 is an operation time chart of the interface circuit shown in FIG. 17, and FIG. 19 is a diagram showing the operation time chart of the interface circuit shown in FIG. The operation time chart figure of the discharge circuit shown in FIG. FIG. 20 shows Example 6 of this invention. FIG. 21 is a detailed connection diagram of the interface circuit shown in FIG. 20, FIG. 22 is an operation time chart of the interface circuit shown in FIG. 21, and FIG.
3 is an operation time chart of the discharge circuit shown in FIG. 20, and FIG. 24 is an embodiment of the present invention. , FIG. 25 is a detailed connection diagram of the interface circuit shown in FIG. 24, FIG. 26 is an operation time chart of the interface circuit shown in FIG. 25, and FIG. FIG. 28 is an operation time chart of the discharge circuit shown in FIG. 24, and FIG. 29 is a diagram showing Embodiment 9 of the present invention.
FIG. 30 is a time chart showing the machining gap voltage of the electrical discharge machining apparatus of Example 10 of the present invention. 31 is an operation time chart of the discharge circuit shown in FIG. 30, FIG. 32, FIG. 33,
FIG. 34 is an explanatory diagram showing the current path of the discharge circuit shown in FIG. 30, and FIG. 35 is an explanatory diagram showing the current path of the discharge circuit shown in FIG. Fig. 36 is a connection diagram of the electrical discharge circuit of the electrical discharge machining equipment.
The operation time chart of the discharge circuit shown in FIG. 5 and FIG. 37 are the operation time charts of the discharge circuit shown in FIG. FIG. 38 is an operation time chart of the discharge circuit shown in FIG. 37. FIG. 39 is a connection diagram of a discharge circuit of a conventional electrical discharge machining apparatus, FIG. 40 is a detailed connection diagram of an oscillation circuit shown in FIG. 39,
41 and 42 are operation time charts of the discharge circuit shown in FIG. 40, FIG. 43 is a connection diagram of the discharge circuit of another conventional electrical discharge machining apparatus, FIGS. 44, 45,
FIG. 46 is an operation time chart of the discharge circuit shown in FIG. 43. In the figure, (1) is the electrode, and (2) is the workpiece. (3), (4301) is the first DC power supply, (6
1, (10), fll13). +3502+, (4302) is a semiconductor switch, (
7) is the oscillation circuit, (9) is the third DC power supply, +to
ll, +3500) is a bypass circuit, (102) is a resistor, (302), (37001 is a discharge interruption detection circuit, +501+ is a reverse voltage application circuit. f502), fl107) is a second DC power supply, t
noo) is voltage setting means, [1600) is voltage application time setting means, f'2000) is discharge pause time setting means, (24001 is discharge voltage application time means, (3
000) is a changeover switch circuit. In addition, in FIG. 1, the same reference numerals indicate the same or corresponding parts.

Claims (10)

[Claims] (1) an electrode disposed facing the workpiece at a predetermined distance; a series circuit of a first DC power supply and a first switch circuit connected between the electrode and the workpiece; a control circuit that controls the first switch circuit on and off to generate a continuous discharge between the electrode and the workpiece; An electrical discharge machining device comprising voltage holding means for holding a voltage between the two at a predetermined voltage. (2) The electric discharge machining apparatus according to claim 1, wherein the voltage holding means comprises a bypass circuit that bypasses electric charge stored between the electrode and the workpiece. (3) The voltage holding means includes a second DC power supply and a second switch circuit connected in antiparallel to a series circuit of the first DC power supply and the first switch circuit between the electrode and the workpiece. 2. The electric discharge machining apparatus according to claim 1, further comprising a reverse voltage applying circuit connected in series with a reverse voltage applying circuit. (4) The voltage holding means is provided with voltage setting means for setting the output voltage of the second DC power supply so that the average voltage between the electrode and the workpiece becomes a predetermined value. 3
The electrical discharge machining device described in Section 1. (5) The voltage holding means is connected in series to a changeover switch circuit that switches one terminal of the first DC power supply from the electrode to the workpiece and the other terminal from the workpiece to the electrode. 2. The electrical discharge machining apparatus according to claim 1, further comprising: (6) Voltage application time setting means for setting the voltage application time by the voltage holding means applied between the electrode and the workpiece so that the average voltage between the electrode and the workpiece becomes a predetermined value. Claim 3 or 5, characterized in that
The electrical discharge machining device described in Section 1. (7) A claim characterized in that a discharge suspension time setting means is provided for setting a discharge suspension time during which application of the discharge voltage is suspended so that the average voltage between the electrode and the workpiece becomes a predetermined value. The electrical discharge machining apparatus according to item 3 or 5. (8) A discharge voltage application time setting means is provided for setting the discharge voltage application time so that the average voltage between the electrode and the workpiece becomes a predetermined value. The electric discharge machining apparatus according to item 5. (9) It has a discharge interruption detection circuit that detects that the discharge is interrupted during the application of the discharge voltage, and a control circuit that turns off the first switch circuit based on the discharge interruption detection signal from the discharge interruption detection circuit. The electrical discharge machining apparatus according to any one of claims 1 to 8, characterized in that: (10) A first DC power supply and a first
A series circuit with a third DC power supply and a third switch circuit connected in parallel with a series circuit with a switch circuit, detecting discharge between the electrode and the workpiece caused by the first DC power supply. Any one of claims 1 to 9, further comprising a discharge detection circuit and a circuit that turns on the third switch circuit for a predetermined period of time based on a discharge detection signal from the discharge detection circuit. The electrical discharge machining device described.